Circuit interrupter

ABSTRACT

A circuit interrupter, such as a switch or a circuit breaker, comprising relatively movable contact means, operating means releasable to open the contact means, and trip means which may be responsive to ground fault currents through the contact means to effect the release of the operating means to open the contact means upon the occurrence of ground fault currents.

United States Patent 1 Wallace et al. a

[111 3,748,609 [4 1 July 24, 1973 CIRCUIT INTERRUPTER [75] Inventors:James B. Wallace; Alfred E. Maier;

Robert 11. Hill, all of Beaver Falls,

[73] Assignee: Westinghouse Electric Corporation,

Pittsburgh, Pa.

[22] Filed: Apr. 18, 1972 [2]] Appl. No.: 245,064

[52] U.S. Cl. 335/174, 335/18 [51] Int. Cl. H01h 9/20 [58] Field ofSearch 335/174, 175, 20,

[ 56] References Cited UNITED STATES PATENTS 2,285,040 6/1942 May335/175 3,470,507 9/1969 Hall et al. 335/174 3,453,568 7/1969 Murphy etal. 335/20 2,508,178 5/1950 Lindstrom et al. 335/40 PrimaryExaminer-Harold Broome Attorney-A. T. Stratton, Lee I. Johns et al.

[57] ABSTRACT A circuit interrupter, such as a switch or a circuitbreaker, comprising relatively movable contact means, operating meansreleasable to open the contact means, and trip means which may beresponsive to ground fault currents through the contact means to effectthe release of the operating means to open the contact means upon theoccurrence of ground fault currents.

12 Claims, 4 Drawing Figures PAIENIEU JUL 24% 3. 748 .609

sum-'2 or 2 FIG. 4

cracurr INTERRUPTER BACKGROUND OF THE INVENTION 1. Field of theInvention This invention relates to circuit interrupters having anenergizable release device for opening the contacts in the interrupterupon the occurrence of ground fault current through the contacts or uponthe application of an energizing current for any purpose.

2. Description of the Prior Art Recently electrical wiring circuits havebeen installed with circuit interrupters such as switches and circuitbreakers that are provided with ground fault trip means for opening thecircuit when a ground fault occurs. Indeed, the desirability ofproviding ground fault protection has been widely accepted in recentyears and has resulted in the production of ground fault devices of thevarious kinds. Among other things, many such devices including groundfault protection that are currently available are unable to open acurrent or circuit interrupter, such as a conventional residentialcircuit breaker, clue to insufficient force generated by the groundcurrent. Accordingly, there is a need for a device for tripping a switchor current interrupter by means of a shunt trip actuated by a groundcurrent or other energizing current.

SUMMARY OF THE INVENTION In accordance with this invention it has beenfound that the foregoing problem may be overcome by providing a circuitinterrupter having relatively movable contact means and means releasableto effect opening of the contact means, trip means including first andsecond levers operable for effecting automatic release of the releasablemeans when a ground fault occurs or energizing current is applied forany purpose, the levers being operable between latched and unlatchedpositions relative to the releasable means, the trip means alsoincluding an electromagnetic trip device responsive to ground faultcurrents through the contacts or the application of an energizingcurrent to effect movement of the first lever to the unlatched position,the trip means being biased in the latched position, the releasablemeans including a releasable lever having an end portion movable betweensaid positions, the second lever having a roller engageable with the endportion in the latched position and being rollable to a nonengagingposition of the end portion in the unlatched position, and a connectinglink extending between the first and second levers.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a vertical sectional viewtaken on the line I-I of FIG. 4 and embodying the principles of theinvention;'

FIG. 2 is a vertical sectional view taken substantially along the lineII-II of FIG. 4 and showing the circuit interrupter in the trippedposition;

FIG. 3 is a vertical sectional view taken on the line Ill -III of FIG. 1and embodying the principles of the invention; and

FIG. 4 is atop plan view of the switch shown in FIG. I.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 of the drawings acircuit interrupter or switch is generally indicated at 10. It comprisesa switch structure 12 which is mounted on a molded base 14 ofelectrically insulating material, and which is disposed between spacedelectrical conductors l6 and 18.

The switch 10 is of the multi-pole type and the mechanism may be of thegeneral type disclosed in U.S. Pat. No. 2,508,178, issued May 16, I950to T. Lindstromet al., and assigned to the assignee of the presentinvention. The switch 10 includes a stationary contact 20 and a movablecontact 22 for each pole of the device. A commonoperating mechanism,generally indicated at 24 (FIG. 1 is provided for simultaneouslyactuating three movable contacts 22 (FIG. 4) to open and closed circuitpositions. The stationary contact 20 is rigidly mounted on the inner endof the conductor 16 which has a line terminal (not shown) connected tothe outer end. The movable contact 22 for each pole is rigidly mountedon a contact arm 28 supported on a switch arm 30 which is rigidlysecured on the end of a tie bar 32 that extends across all of the poles(FIG. 4) of the switch for movement together to open and closed circuitpositions. The contact arm 28 is connected by a flexible conductor 34 tothe conductor 18 which is se cured to the base 14 in a suitable mannersuch as by a screw (not shown). 3;

The operating mechanism 24'for the switch structure 12 is disposed inthe center compartment (FIG. 4) of the mechanism and is supported on apair of laterally spaced frames 36 and 38 which are secured to the base14 by suitable means such as screws 40. The operating mechanismcomprises a forked operating lever 42, a toggle comprising links 44 and46, overcenter springs 48, and a releasable lever or pivoted cradle 50.An arcuate insulating shield 52 is mounted over the operating and of theoperating lever 42 and is provided with an integral switch handle 54.The shield 52 is mounted over an intermediate portion 56 of theoperating lever 42 and is secured in place by suitable means such asscrews 58 attached to the forked portions of the lever 42, only one ofwhich is shown in FIG. 1.

The toggle links 44 and 46 are pivotally connected together by a kneepivot pin 60. The toggle link 44 is pivotally connected by a pivot pin62 to the cradle 50 and the toggle link 46 is pivotally connected to theswitch arm 30 for the center pole by a pivot pin 64. The overcentersprings 48 are connected under tension between the knee pivot pin andthe outer end of the operating lever 42 at pivot pin 66.

The switch structure for the circuit breaker 12 is operated to the openoperating position by manipulation of the handle 54 in a clockwisedirectionto the oft position, actuating the overcenter springs 48 tocause collapse of the toggle links 44 and 46 (FIG. 2), thereby causingopening movement of the switch arms 30 for all of the poles-of theswitch in a well-known manner.

Trip means are provided for automatically opening the switch 10 when aground fault occurs or an energizing current is applied. The trip meansbeing generally indicated at 63 comprises a "knuckle" type linkage whichis movable between latched and unlatched positions with regard to thecradle 50. In the latched position, the knuckle linkage goes overcenter"and the linkage is held in tension (FIG. 1) by the springs 48 of theoperating mechanism 24. More particularly, the trip means 63 includes(FIG. 2) a lever 65, a lever or bellcrank 67, a roller 68, and a biasingspring 70. In addition, the trip means 63 includes an electromagneticdevice such as a solenoid 72 (FIGS. 2 and 4) having a plunger 74. Thesolenoid 72 is suitably mounted such as by a bracket 76 on a supportingframe of the circuit breaker, as shown in FIG. 4, where the plunger 74is adapted to move the lever 65 in response to any abnormal currentoccurring through the contacts 20 and 22 as the result of a groundfault.

The lever 65 is mounted on the frame 36 (FIG. 1) by a pivot pin 78. Thelever 65 is provided with a flange 80 by which the lever is movedclockwise to the position shown in FIG. 2 by the plunger 74 when thesolenoid 72 is actuated. The bellcrank 67 is pivotally mounted on theframe 36 by a pivot pin 82 and cooperates with a shaft support member 84for mounting the shaft 86. The preferred construction of the bellcrank67 and the shaft support member 84 includes an interconnecting portion88 which with the bellcrank and support member form a U-shaped unit thatis disposed between the frames 36 and 38. The shaft support member 84 ispivotally mounted on the upper end of the frame 38 by a pivot pin 90(FIG. 3). The shaft 86 supports the roller 68 which is rotatably mountedon the shaft and which cooperates with the cradle 50 in a manner setforth below.

The bellcrank 67 includes an outturned portion 92 which extends to theright as viewed in FIGS. 1 and 2. A connecting link 94, as best shown inFIG. 2, extends between the bellcrank 67 and the lever 65. A pivot pin96 connects the link 94 to the bellcrank 92 and a pivot pin 98 connectsthe link to the lever 65. The spring 70 which is mounted on the pivotpin 96 has opposite end portions connected to the lever 65 and thebellcrank 67 for biasing the trip means 63 in the counterclockwise orlatched position as shown in FIG. 1.

During normal operation of the circuit breaker the trip means 63 isdisposed in the latched position with the roller 68, composed of a hardmaterial such as hardened steel, disposed over an end portion 50a on theupper side of the cradle 50 to hold the cradle in the lowermost(latched) position. In that position, the contacts and 22 may be openedand closed in a normal manner by manual manipulation of the handle 54 inthe clockwise and counterclockwise directions. Thus, the cradle 50 isretained in the latched position under normal electric currentconditions. When an abnormal operating condition occurs such as a groundfault, the condition is detected by conventional ground fault detectiondevice (not shown) which device transmits an electric current to thesolenoid 72, causing the plunger 74 to move outwardly (to the right asviewed in FIG. 2) and to thereby rotate the lever 65 clockwise to theposition shown. This action moves the roller 68 away from the latchedposition of FIG. 1 and the cradle 50 is thereby free to rotatecounterclockwise about its mounting shaft 102 the ends of which areseated in the spaced-frames 36 and 38. Upon release of the cradle 50,the springs 48 operate to pivot the cradle counterclockwise about itspivot and to change the line of action of the springs so that thesprings collapse the toggle links 44 and 46 from the extended positionsof FIG. 1 to the collapsed position of FIG. 2 and to thereby raise thecontact arm 28 to the open position in a conventional manner.

Upon opening of the contacts 20 and 22 the energizing current may bediscontinued or the ground fault which tripped the mechanism iscorrected and the plunger 24 moves to the left or retracted position,

whereupon the spring acts to return the trip means 63 to the latchedposition. However, inasmuch as the roller 68 is now disposed against anend 104 of the cradle 50 (FIG. 2), it is necessary to manually move thehandle 54 to a resetting position in a manner well known in the art.Thus, the handle 54 is manually rotated clockwise until a flange 106 ofthe intermediate portion 56 is brought into contact with an end 108 ofthe cradle 50 to rotate the cradle clockwise until the end 104 islowered and the end portion 50a drops below the roller 68 to the latchedposition. The switch 10 is then in condition for reclosing the contacts20 and 22 by rotating the handle 54 counterclockwise to the positionshown in FIG. 1.

Accordingly, the device of the present invention satisfies problems thatexisted in the prior art with regard to ground fault phenomena. Thedevice is particularly adapted for tripping a fusible switch by means ofa shunt trip actuated by a ground current or an energizing currentwhereby a solenoid uses a minimal amount of force (ounces) to actuate arelatively much higher latch load (pounds); i.e., the device provides ahighly satisfactory and advantageous mechanical advantage. Finally,prior art circuit interrupters of the general type described have notincluded suitable means for tripping the breaker upon the occurrence ofa ground fault through the contacts or application of an energizingcurrent.

What is claimed is:

l. A circuit interrupter comprising relatively movable contact means andmeans releasable to effect opening of the contact means, the releasablemeans comprising a releasable lever, trip means comprising tensionlinkage including first and second levers and a connecting link operablefor effecting automatic release of the releasable means, the first andsecond lever being pivotally mounted respectively on first and secondpivot pins, the connecting link being pivotally mounted on the first andsecond levers respectively on third and fourth pivot pins, the first andsecond levers being operable between latched and unlatched positionsrelative to the releasable lever, the trip means also including anelectromagnetic trip structure adapted to respond to an energizingcurrent to effect movement of the first lever to the unlatched position,and the second lever being movable by the first lever from latch tounlatched positions of the releasable lever upon operation of theelectromagnetic trip structure.

2. The circuit interrupter of claim 1 wherein the trip structure isbiased in the latched position.

3. The circuit interrupter of claim 1 wherein the electromagnetic tripstructure is operable to move the first lever to the unlatched position.

4. A circuit interrupter comprising relatively movable contact means andmeans releasably to effect opening of the contact means, the releasablemeans comprising a releasable lever, trip means comprising tensionlinkage including first and second levers and a connecting link operablefor effecting automatic release of the releasable means, the first andsecond lever being pivotally mounted respectively on first and secondpivot pins, the connecting link being pivotally mounted on the first andsecond levers respectively on third and fourth pivot pins, the first andsecond levers being operable between latched and unlatched positionsrelative to the releasable lever, the trip means also including anelectromagnetic trip structure responsive to abnormal ground faultcurrents to effect movement of the first lever to the unlatchedposition, and the second lever being movable by the first lever fromlatched to unlatched positions of the releasable lever upon operation ofthe electromagnetic trip structure.

5. The circuit interrupter of claim 4 wherein the trip structure isbiased in the latched position.

6. The circuit interrupter of claim 4 wherein. the electromagnetictripstructure is operable to move the first lever to the unlatched position.

7. The circuit interrupter of claim 4 wherein the releasable lever ismovable between latched and unlatched positions when the trip means isreleased, and the second lever having means engageable with thereleasable lever in the latched position.

8. The circuit interrupter of claim 7 wherein the engageable means is aroller engageable with the releasable lever in the latched'position, androllable to a nonengaging position of the end portion in the unlatchedposition.

9. The circuit interrupter of claim 7 wherein the trip means are biasedin the latched position.

10. The circuit interrupter of claim 9 wherein the second'lever is abellcrank.

11. The circuit interrupter of claim 9 wherein the application of asmall force by the electromagnetic trip structure on the first levereffects a substantially larger force on the second lever.

12. The circuit interrupter of claim 9 wherein the contact meanscomprise a stationary contact, a movable contact, and a movable switcharm having the movable contact thereon; the releasable means comprisingan operating lever, a switch handle, the releasable lever, an overcentertoggle operable by the operat ing lever to effect movement of the switcharm to opened and closed circuit positions, and the overcenter togglebeing operatively connected between the releasable lever and the movableswitch arm.

1. A circuit interrupter comprising relatively movable contact means andmeans releasable to effect opening of the contact means, the releasablemeans comprising a releasable lever, trip means comprising tensionlinkage including first and second levers and a connecting link operablefor effecting automatic release of the releasable means, the first andsecond lever being pivotally mounted respectively on first and secondpivot pins, the connecting link being pivotally mounted on the first andsecond levers respectively on third and fourth pivot pins, the first andsecond levers being operable between latched and unlatched positionsrelative to the releasable lever, the trip means also including anelectromagnetic trip structure adapted to respond to an energizingcurrent to effect movement of the first lever to the unlatched position,and the second lever being movable by the first lever from latch tounlatched positions of the releasable lever upon operation of theelectromagnetic trip structure.
 2. The circuit interrupter of claim 1wherein the trip structure is biased in the latched position.
 3. Thecircuit interrupter of claim 1 wherein the electromagnetic tripstructure is operable to move the first lever to the unlatched position.4. A circuit interrupter comprising relatively movable contact means andmeans releasably to effect opening of the contact means, the releasablemeans comprising a releasable lever, trip means comprising tensionlinkage including first and second levers and a connecting link operablefor effecting automatic release of the releasable means, the first andsecond lever being pivotally mounted respectively on first and secondpivot pins, the connecting link being pivotally mounted on the first andsecond levers respectively on third and fourth pivot pins, the first andsecond levers being operable between latched and unlatched positionsrelative to the releasable lever, the trip means also including anelectromagnetic trip structure responsive to abnormal ground faultcurrents to effect movement of the first lever to the unlatchedposition, and the second lever being movable by the first lever fromlatched to unlatched positions of the releasable lever upon operation ofthe electromagnetic trip structure.
 5. The circuit interrupter of claim4 wherein the trip structure is biased in the latched position.
 6. Thecircuit interrupter of claim 4 wherein the electromagnetic tripstructure is operable to move the first lever to the unlatched position.7. The circuit interrupter of claim 4 wherein the releasable lever ismovable between latched and unlatched positions when the trip means isreleased, and the second lever having means engageable with thereleasable lever in the latched position.
 8. The circuit interrupter ofclaim 7 wherein the engageable means is a roller engageable with thereleasable lever in the latched position, and rollable to a non-engagingposition of the end portion in the unlatched position.
 9. The circuitinterrupter of claim 7 wherein the trip means are biased in the latchedposition.
 10. The circuit interrupter of claim 9 wherein the secondlever is a bellcrank.
 11. The circuit interrupter of claim 9 wherein theapplication of a small force by the electromagnetic trip structure onthe first lever effects a substantially larger force on the secondlever.
 12. The circuit interrupter of claim 9 wherein the contaCt meanscomprise a stationary contact, a movable contact, and a movable switcharm having the movable contact thereon; the releasable means comprisingan operating lever, a switch handle, the releasable lever, an overcentertoggle operable by the operating lever to effect movement of the switcharm to opened and closed circuit positions, and the overcenter togglebeing operatively connected between the releasable lever and the movableswitch arm.